The present invention relates to apparatus which is particularly adaped for use in the electrolytic production of alkali metal hydroxide. More particularly, the instant invention is useful in electrolytic cells which are particularly suited for the production of chlorine and caustic and will be described with particular reference thereto; however, it will be appreciated by those skilled in the art that the invention has broader applications and may be employed in other environments.
Chlorine and caustic are commonly produced by the electrolysis of brine and details of the specific apparatus utilized for this purpose vary. However, the bulk or majority of chlorine and caustic produced in the world today is produced by means of either what is commonly referred to as the mercury cell and/or what is commonly referred to as the diaphragm cell. Both of these types of cells are deemed well known in the art.
In the diaphragm cell, chlorine and caustic are produced by passing electric current between an anode and a cathode which are separated from each other by a diaphragm. Conventionally, the anode is comprised of graphite while the cathode is fabricated from steel. In addition, the diaphragm normally comprises an asbestos base material.
Recently, such cells have been greatly improved by incorporating therein dimensionally stable anodes. Such anodes have been made by depositing noble metals, alloys, oxides or mixtures thereof on a valve metal. Further, the asbestos diaphragm has been replaced with a permselective membrane. Typical of such membranes are those fashioned from a hydrolyzed copolymer of a perfluorinated hydrocarbon and a fluorosulfonated perfluorovinyl ether.
The above referred to innovations have significantly enhanced the electrical operating efficiency of conventional diaphragm cells. However, in addition, further efficiency in their operation has been realized by modifying the general physical structure of these cells and it is with regard to certain of these latter modifications that the subject invention is directed.
Specifically, one type of modified diaphragm cell includes at least two juxtapositioned cell modules having a permselective membrane member positioned therebetween. Each of the cell modules includes a housing, an anode, a cathode and a fluid impermeable web member positioned between the anode and cathode members to form, respectively, individual anode and cathode compartments. The housing includes a first header communicating with the supplying fluid or liquid to the anode compartment and a second header communicating with and supplying fluid or liquid to the cathode compartment. Fluid can be metered into the anode and/or cathode compartments via their respective headers. Each cell module is also provided with convenient means for removing the resultant products of electrolysis therefrom.
In operation, a plurality of the cell modules are employed with each juxtapositioned cell module separated from the other by means ofa permselective membrane. Electrolysis of the appropriate fluid or liquid brine is then effected between the anode of one cell module and the cathode of the next cell module. Since the general operational and constructional features of the foregoing type of cell are known to those skilled in the art, specific means of activation and operation will not be discussed herein in detail.
While electrolytic cells of the foregoing type have performed adequately in some circumstances, one serious problem has been encountered during cell operation. This problem relates to the fact that the areas of communication between the headers and the cathode and anode compartments have become blocked. Typically, these areas of communication merely comprise small openings or orifices extending between the headers and compartments. Because of their small size location within the cells, it is both difficult and time consuming to clear the openings once they have become blocked. Since the headers and cell module housings are often times integrally cast or formed, it becomes necessary to disassemble and/or replace portions of an entire electrolytic cell. Obviously, this necessity is extremely undesirable if continuous efficient cell operation is to be achieved.
The present invention contemplates a new and improved structure which overcomes the above referred to problems and others and provides a new and improved removable orifice structure which is simple, economical, easily and positively removed from a cell structure for cleaning or replacement purposes and which is readily adaptable to use in a number of different environments.